1. Field of the Invention
The present invention relates to an electrophotographic image forming apparatus.
2. Description of the Related Art
As an electrophotographic image forming apparatus, which forms a multi-color image or a full-color image by using an electrophotographic printing method, there has been known an image forming apparatus of an inline type or a tandem type, including a plurality of photosensitive members which are aligned substantially in a line. Here, the electrophotographic image forming apparatus is an apparatus that forms an image on a recording medium by using an electrophotographic image forming process. As the electrophotographic image forming apparatus, there are exemplified, for example, an electrophotographic copying machine, an electrophotographic printer (for example, color laser beam printer and color LED printer), a multi-function printer (MFP), a facsimile machine, and a word processor. The electrophotographic image forming apparatus forms toner images of different colors (for example, yellow, magenta, cyan, and black) on respective multiple image bearing members (hereinafter referred to as a photosensitive drum). The toner images of different colors are sequentially transferred onto a recording medium to be superimposed. The superimposed toner images are heated and pressurized to be fixed onto the recording medium, to thereby form a color image. Here, the recording medium is one on which an image is formed by the electrophotographic image forming apparatus, and paper, an OHP sheet, cloth, and the like are included therein, for instance.
Around the photosensitive drum, process means such as a charging means, an exposing means, a developing means, a transfer means, and a cleaning means, are arranged. Note that, there is known one in which a part of those process means is removably mounted, as a process cartridge, to a main body of the electrophotographic image forming apparatus. The process cartridge is removably mounted to the main body of the electrophotographic image forming apparatus, and contributes to an image forming process of forming an image on a recording medium. Here, in the process cartridge, at least one of the charging means, the developing means, and the cleaning means each serving as the process means and an electrophotographic photosensitive drum are integrated into a cartridge, and the process cartridge is removably mounted to the main body of the electrophotographic image forming apparatus. The process cartridge is removably mountable to the main body of the electrophotographic image forming apparatus by a user him/herself. Therefore, maintenance of the apparatus main body may easily be performed.
As the transfer method, there is known an intermediate transfer method, in which the toner images formed on the plurality of photosensitive drums are transferred in advance onto an intermediate transfer member, and then transferred onto a recording medium. As the intermediate transfer member, there is known a transfer means in which an intermediate transfer belt (transfer member) is used. In the transfer means of the intermediate transfer type, the toner images formed on the plurality of photosensitive drums are sequentially primarily transferred onto the intermediate transfer belt, and the plurality of toner images are superimposed on the intermediate transfer belt. Then, the toner images superimposed on the intermediate transfer belt are secondarily transferred on a recording medium.
As another transfer method, there is known a tandem method, in which the toner images formed on the plurality of photosensitive drums are sequentially transferred onto a recording medium on the transfer belt. The transfer belt used in the tandem method functions as a recording medium conveying member configured to convey a recording medium through electrostatic attraction. There is known a transfer means in which a transfer belt (transfer member) is used.
In order to facilitate the maintenance of the electrophotographic image forming apparatus (hereinafter referred to as an image forming apparatus), there is known an image forming apparatus in which the transfer means is removably mounted to the main body of the image forming apparatus (hereinafter referred to as an apparatus main body). The transfer means, which uses a transfer member, is movable between a mounting position inside the apparatus main body, at which the transfer means is mounted to the apparatus main body and a removing position outside the apparatus main body, at which the transfer means is removed from the apparatus main body. In such an image forming apparatus, the transfer means is moved between the mounting position and the removing position in a state in which the transfer member is in contact with the photosensitive drum, there is a fear of making a scratch on the photosensitive drum or the transfer member. The scratch marked on the photosensitive drum or the transfer member may cause a failure of image. In order to prevent the scratch marked on the photosensitive drum or the transfer member, there is proposed a structure in which, when pulling out the transfer means, the photosensitive drum is separated from the transfer member (Japanese Patent Application Laid-open No. 2006-184901).